Fibres from the two main divisions of trees, hardwoods and softwoods differ considerably and give distinct properties to the resultant paper.
Softwood fibres, commonly from pine, spruce and fir are long (2-3.5mm). Long fibres give the paper/board strength, but also rough. Hardwood fibres such as eucalyptus and poplar are shorter (1-1.5mm) and although weaker, can provide a smoother surface for printing. Usually a combination of fibre types provides the optimal performance.
Fibres are identified by comparison with a microphotograph of reference fibres and the ratio of the mix of types of fibres is estimated. A weighting factor is used in the calculations for the ratios of the different fibres.
Standards and Accreditation
Quantitative fibre furnish analysis is made in accordance with British standard BS 7463, International standard ISO 9184 and BPBIF PP No.50 by microscopic examination of a dried suspension of fibres.